The present invention relates to a color image copying apparatus and, more particularly, to a color image copying apparatus using a color image sensor.
Conventional color copying apparata include a type using an electrophotography technique and another type using a color drum scanner.
The copying apparatus of the electrophotographic type encounters difficulty in copying an original or subject copy, bearing a high or low density picture, with a satisfactory picture quality. In this type of copying apparatus, exposure conditions for the original must be altered according to the density of the original. However, it is difficult to finely and uniformly adjust the exposure conditions for three primary color components of the color picture. For this reason, the hue of the copy is frequently different from that of the original.
In the copying apparatus using the color drum scanner, a picture signal is usually not separated into a luminance signal component and color difference signal components. To alter the state of a copy according to the density of the original, the three primary color components must be changed simultaneously. The change of each of the three primary color components is frequently accompanied with a change in the hue of the copied picture.